1. Field of the Invention
The present invention relates to a disk drive and more specifically to a disk drive capable of writing data signals into a disk and/or reading data signals recorded in the disk on both sides of the disk and a method of controlling the disk drive.
2. Description of the Related Art
Conventionally, so-called double-sided reproducing disk drives capable of writing data signals into a disk and/or reading data signals recorded in the disk (hereinafter, occasionally referred to simply as recording and/or reproducing data signals) on both sides of the disk have been known; for example, one of which is disclosed in Japanese Patent Laid-Open Publication No. 7-320276.
In this prior art disk drive, there is provided a U-shaped guide rail which extends from one side to the other side of the disk, and while a turn table for supporting and rotating a disk remains stationary, an optical pickup travels along the guide rail to record and/or reproduce data signals on both the sides of the disk.
It is essential for recording and/or reproducing the data signals on the disk that the optical axis of the optical pickup is precisely held vertical to the surface of the disk to be scanned (specifically, a disk supporting surface of the turn table). Particularly, in a case of a disk with high recording density such as the so-called DVD disk (digital video disk or digital versatile disk), as the light emitted from the optical pickup is focused to a spot of very small size on a disk and the rotation of the disk is much higher, the accuracy of verticality has to be increased correspondingly.
The prior art double-sided reproducing disk drives allows the optical pickup to move from one side to the other side of the disk for recording and/or reproducing data signals on the other side of the disk when the recording and/or reproducing action on the one side of the disk has been completed, while the turn table remains stationary. Accordingly, the positional relationship between the optical pickup and the turn table is not constant but varies whenever the side of the disk to be scanned for the recording and/or reproducing action is alternated from one side to the other side. It is thus troublesome to maintain the optical axis of the pickup vertical to the surface of the disk to be scanned with a high degree of accuracy.